<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
	<style type="text/css">
		*{
			margin: 0;
			padding: 0;
		}
		.box{
			width: 400px;
			height: 400px;
			background: skyblue;
			margin: 0 auto;
			margin-top: 100px;
			position: relative;
		}
		.circle{
			width: 100px;
			height: 100px;
			background: pink;
			border-radius: 50%;
			position: absolute;
			left: 50%;
			margin-left: -50px;
			top:-50px;
			text-align: center;
			line-height: 100px;
		}
	</style>
</head>
<body>
	<!-- 
		子绝父相： 父元素设置相对定位， 子元素设置绝对定位
	 -->
	 <div class="box">
	 	 <div class="circle">LOGO</div>
	 </div>
</body>
</html>